Bring a large pot of water to a boil. Add the kale, stir to submerge the leaves, and cook over high heat until wilted and somewhat tender but still bright green, about 3 minutes. Drain and set aside to drip dry.

Heat the oil in a medium sautee pan. Add the onions and garlic and sautee over medium heat, stirring frequently, until beginning to turn golden, about 6 minutes. Remove from heat and set aside.

Break the eggs into a large bowl and lightly beat. Add the feta, half-and-half, kale, onion mixture, and salt. Stir to mix and pour into the prebaked crust. Bake until the center of the pie is firm and lightly golden across the top, 40 to 45 minutes. Remove and allow to cool 10 to 15 minutes. Serve while still warm or serve at room temperature. Serves 4.